First post here - so please go easy on me - I'm also relatively new to vintage macs...
I recently acquired a Mac LC475. Having been cleaned, re-capped, PRAM battery fixed up - and the case glued where needed it's now ready to go. It had a collection of random, non-working stuff on the drive (running System 7.1) - so I thought I'd re-format it and put macOS 7.5 on there - as that seems to be about "peak" for this machine from what I've read (or maybe 8.1?).
The machine has also been "chipped" by the previous owner taking it from 25Mhz to 33Mhz. As such the "About this mac" dialog now just says "Macintosh" instead of "Macintosh LC475" (which is I think where my trouble lies).
I have a CD-ROM drive for the machine - and managed to download one of the Apple Legacy Restore CD's - this boots fine, but I can't install anything older than 7.1 - as all later versions pop up with "Installer script does not recognize this Macintosh. Please use the original ..."
I'm guessing this is because it's looking at the machine ID - and not finding anything it recognizes any more so won't install. System 7.1 does install - but none of the updaters to newer versions run either.
I'm also aware of the "Wish I were" utility - to fix this is it going to be as simple as booting from the CD, running Wish I were from floppy - and re-picking the LC475 - then running the installer?
If not - is there anything I can do to bypass this check?
I've looked around both these forums - and the net, and not really found a lot of info about it. In fact, there's comparatively little info about older mac's floating around - so it's great I found this place!
You could install on another macine or VM, copy the system folder and whatever else you want other, and then bless the system folder. There are utilities to bless, but IIRC, the way I used to do it was to remove System from the old system folder, then open the new System folder and it would automatically bless.
System software prior to 7.1 simply doesn't support the LC 475, or any other Mac made after 1992.
Sorry - my bad, I meant 'newer' than 7.1 Working with old stuff it gets confusing...
Ok I managed to sort this now by using an emulator - and installing to a virtual drive - when I then dd'd (copied) over the original drive.
This works - but it's a bit of a pain - I'm surprised no one has come up with either a modified installer - or any other workaround.
Specific to the Gestalt ID problem: "About this Macintosh" saying "Macintosh" rather than the actual model name is a System 7.5 artifact. The installer probably did bomb out because the ID was unrecognized, but "About this Macintosh" is useless on 7.5.
When I was refurbishing a few Quadras, I ran into this. I'm ex-Apple, and although I wasn't around for the pre-Intel Macs, my old manager was. He said that there was an issue with that dialog box not properly parsing the Gestalt ID, and pointed me towards "Mac Identifier" as a way to work around the issue.
It's available on Macintosh Garden here. It's worthwhile to install it, to see what your Gestalt ID is being reported as. System 7.5 did some sneaky things to see what it was installed on (most notably the serial port clock rate check to distinguish between a Centris 650 and a Quadra 650).